Aiya Kyu and Aneko Yusagi’s Rising of the Shield Hero is a manga adaption of Yusagi’s light novel series of the same name. It is an isekai portal fantasy.
Finding himself short on cash, twenty-year-old student Naofumi Iwatani takes refuge in a convenient library. A fantasy novel catches the otaku’s interest when it falls off a shelf onto his head. He scans it briefly and decides that its scenario — four chosen ones saving their world — seems too contrived. No sooner does this thought cross his mind when he is transported to the world within the tome. He’s one of the four chosen ones.